1. Field of the Invention
The present invention relates to a conversion adapter for making a connection between two devices each having signal input/output connectors assuming a different configuration with respect to each other.
2. Description of the Related Art
As illustrated in FIG. 7, a multisync display 1 which is connectable to multiple computers is connected by a connector 1a to a computer 3 having an output connector 3b via connectors 2a of a signal cable 2. The output connector 3b of the computer may have a different configuration than connector 2a, and in this case, the connection is performed typically by interposing a conversion adapter 4 between the connector 2a of the signal cable 2 and the connector 3b of the computer 3. For instance, the connector 1a of the display 1 and the connector 2a of the signal cable 2 are each designed for 9 pins, while the connector 3b of the computer 3 is appropriate for 15 pins. One connector 4a of the adapter 4 thus is designed for 9 pins, while the other connector 4b is suited to 15 pins.
As is known, as the number of connections between the computer and the display increases, the more unnecessary radiation is caused which, in turn, causes more noise which must be strictly regulated. This unnecessary radiation is produced because the signal cable serves as a kind of antenna. A well-known method of eliminating such unnecessary radiation involves a step of inserting noise filters, for cutting off high frequency components by which the unnecessary radiation is caused, in a video signal line in the vicinity of the output of the computer.
Under such circumstances, it has been considered desirable to eliminate such unnecessary radiation by incorporating the above-described noise filters into the conversion adapter 4. Such noise filters are, however, required to have a sharp cut-off property. Hence, each noise filter should be a 3-terminal noise filter of the type depicted in FIG. 6. For this reason, an input/output wire arrangement for the conversion adapter 4 becomes complicated.
In the case of a color display, particularly when there are provided five signal lines (viz., R, G, B, horizontal synchronization and vertical synchronization), for example, the number of noise filters must be increased. This results in a more complicated wire arrangement and renders it quite difficult to incorporate the noise filters into the conversion adapter. Namely, it is quite troublesome to connect a multiplicity of wires led from the input/output connectors of the conversion adapter 4 to predetermined terminals of predetermined noise filters because there are so many portions to be connected. This arrangement is undesirable and unpracticable for use in mass production.
In the conventional conversion adapter having no noise filter, on the other hand, the above-mentioned unnecessary radiation noises cannot be obviated. Therefore, in the example shown in FIG. 7, more than two kinds of signal cables 2 are prepared in which the connector 2a disposed on the side of the computer 3 is suited to 9 pins or 15 pins in order to cope with such a problem. However, the preparation of a plurality of signal cables for this purpose involves a relatively intricate arrangement.